Class RailsThinker < Rails

Rails and Amazon Web Services

2009-11-16T15:27:00.000-08:00

Hi all,

One of the Most wanted skills in Ruby on Rails right now is "Rails and Amazon: Libraries and Plugins for EC2, S3, SimpleDB, SQS, FPS and DevPay Integration". The below link will much useful those who are looking to learn about these integartions.

http://bit.ly/yQsuS

Rails become like a ocean now itself, just think after the official release of "Rails 3". That should be a cyclone on web development industries.

Think more about "Rails", do more development :)

Simple Array Comparison in Ruby

2009-10-21T19:47:00.001-07:00

Here is a simple method to compare two arrays using Ruby, few examples:

> [1,2,3] <=> [1,2,3]
=> 0
> [1,2,3] <=> [2,2,3]
=> -1
> [1,2,3] <=> [3,2,3]
=> -1
> [1,2,3] <=> [1,3,3]
=> -1
> [1,2,3] <=> [1,1,3]
=> 1

By use of Terinary Operator (<=>), we can acheive the simple method to compare two arrays of comparison.

Hope this will help for someone or me in future!!!

Get Start/Switch your projects with Ruby On Rails

2009-07-03T02:38:00.000-07:00

For this past few years i missed to read an wonderful article about the succession of Ruby on Rails. This article explains us "How Ruby on Rails succeeded and intention to Create this?" Dont ever miss any one to read this article. Just click the below link and start to work with Ruby on Rails.

http://tinyurl.com/kopbwe

For each and every programmers or technicians or business development managers, this article should read and need to get know about Ruby On Rails(ROR).

Especially in India, so much of them didnt even know about this framework and language. Some bigger companies are not yet started to accomodate this simple framework( rails ) with the base powerful language (ruby). They should come over and start to work on this technology. Its the only language now the direct competitor for Java in the whole world. In Denmark, it almost 90% of programmers using this framework.

It Benefits a lot. In Brief,

-> Reduce the number of hours to develop a application.
-> Reduce the number of developers involved to create a application.
-> Reduce the stress, energy to create the applications by the developers.
-> Easy to learn the framework.
-> More compatible with all platforms.
-> Easy to implement the Agile methods.

Finally, Last but not Least, its everthing "OPEN SOURCE". Get think over the above advantages and start / switch your projects with Ruby On Rails.

Happy coding and will see you in another information.

Searching String(s) in file(s) using Ruby

2009-06-13T08:14:00.000-07:00

Searching String(s) in file(s) using Ruby is very simiple. Here is the sample code to manipulate it.

# searching a string in a file
def print_line_containing(file, str)
File.open(file).grep(/#{str}/).each do |line| puts "#{line}" end
end

# searching multiple strings in a file
def print_line_containing(file, str1, str2)
File.open(file).grep(/#{str1}\s+#{str2}/).each do |line| puts "#{line}" end
end

# searching multiple strings in multiple files
def print_line_containing(file_array, str)
file_array.each do |file|
File.open(file).grep(/#{str1}\s+#{str2}/).each do |line| puts "#{line}" end
end
end

I hope this will help you all!

Building Shopping Cart with Ruby on Rails in few minutes

2009-06-10T08:29:00.000-07:00

we can easily build a shopping cart application in a fraction of few minutes.

http://code.google.com/p/substruct/

Use the above link and download the substruct application. Follow the instructions like installation, svn updating the substruct engine, and etc., from the left nav bar on that page.

Then you will get the shopping cart application with payment integration with the Active Merchant plugin.

Get use of open source and explore your thoughts with your application.

Array Mapping in Ruby

2009-05-22T10:48:00.000-07:00

Hi to All,

Here is the sample code to know the usage of array mapping in Ruby.

>> User.find_all_by_office_id(20)
=> [#, #]

If you want to map only the User id's from the above result set. then you should use like this:

>> User.find_all_by_office_id(20).map(&:id)
=> [1032, 3646]

If you want to use these User id's in an another query with "IN" predicate. Then you should use like this:

>> User.find_all_by_office_id(20).map(&:id).compact.join(",")
=> "1032,3646"

the compact will you delete the blank array element from the result set.

then it joins with "," (comma). So finally you will get the string with concatenated id's with comma. You can use this string in the another query with "IN" predicate, like this

>>user_ids = User.find_all_by_office_id(20).map(&:id).compact.join(",")

>>y Website.find(:all, :conditions => "user_id in(#{user_ids})")

you will the websites list for these users.

Rails 2.3.2 bugs with solutions

2009-04-17T09:04:00.001-07:00

For the rails thinkers this link may helpful a lot to solve their basic issues with recent rails released version 2.3.2

http://tiny.cc/67kLX

Gem Capistrano issue on Ruby on Rails

2009-04-17T01:55:00.000-07:00

If you are going to use capistrano gem for deployment.

you should install two gems for this:

sudo gem install capistrano
sudo gem install capistrano-ext

If you missed out "capistrano-ext" gem to install,

it wont you to execute capistrano operations like deploy, log, etc., i.e tasks which are using your deploy.rb

/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require': no such file to load -- capistrano/ext/multistage (LoadError)

and it returns the above error.

Rmagick and ImageMagick Installation steps in Ubuntu

2009-04-15T08:00:00.000-07:00

Hi to all,

After 1 to 2 hours struggling with the Rmagick and ImageMagick Installation in Ubuntu 8.10, i have found a simpler steps to do:

1) Install "imagemagick" through apt-get or synaptic manager.
2) Again Install "libmagick9-dev" through apt-get or synaptic manager.
3) Then, sudo gem install rmagick ( recent version will get install )

If you want a specific version of rmagick, then use this
sudo gem install rmagick -v 1.15.12

Note: rmagick 1.15.12 version is a stable gem.

To install rubygems in Ubuntu

2009-04-14T09:05:00.000-07:00

I prefer these commands to install updated RubyGems in Ubuntu. Use the below commands on your terminal and get it quicker.

sudo gem install rubygems-update
sudo update_rubygems

Rails on Git

2009-03-26T09:35:00.000-07:00

Git is one of the extreme repository storage media. Its similar kind of Subversion(SVN), CVS, Mercurial, etc revisioning system. Its pretty much useful for rails kind of frameworks. Even our Rails gem also switched to Git repository from SVN.

I feel more happy to work with it. Its fast and furious. i'll suggest you to adopt into this technology.

Today i have found one superb tool to find the difference and merging the conflicted file by comparing between the local and remote files with Good GUI.

man page for git mergetool

meld is one of the tool to find the difference between multiple files. Use the below command to run the tool.

git mergetool -tool=meld

Sample Dispaly for this tool:

I will update about GIT regularly on either gokulamurthy.blogspot.com or on this.
Keep Updating your knowledge.

Rails 2.3 Features or Enhancements

2009-03-23T08:40:00.000-07:00

Hi Friends,

Rails 2.3 is successfully launched and excited to work with it. Here is the brief features list:

From the below rails 2.3 release notes link you may get the summary of each above features.

http://guides.rubyonrails.org/2_3_release_notes.html

Enjoy Coding with Rails!

map method is one of the best methods in rails

2009-03-20T07:42:00.000-07:00

This methods will turns the symbol to proc.

Here is an example:

>> tcs = TemplateCompatibility.find :all, :select => "DISTINCT id, template_id"
=> [#"1", "id"=>"1"}>, #"2", "id"=>"2"}>, #"3", "id"=>"3"}>, #"4", "id"=>"4"}>, #"5", "id"=>"5"}>, #"6", "id"=>"6"}>, #"7", "id"=>"7"}>, #"4", "id"=>"8"}>]

If you want to extract a specific field from the above result set or an array, here in the above example i want to extract specifically template_id values, then we can use "map" method to get the values in a new array. Here is the syntax to use it with this example.

>> tcs.map(&:template_id)
=> [1, 2, 3, 4, 5, 6, 7, 4]

Enjoy Coding & hacking too!

Difference Between rspec and rspec-rails gems/plugins

2009-03-19T22:24:00.000-07:00

rspec gem or plugin => basic rspec without rails support (runner, rake
task, api for describe/it, should etc)

rspec-rails gem or plugin => extra support for rails model view and
controller, database integration, code generation (script/generate)

It doesn't matter whether you use the gem or the plugin. Just pick one
that suits your project.

Free E-Magzines for Rails

2009-03-17T08:35:00.000-07:00

"The Rubyist" and "Rails Magazine" are the magazines has announced to download their issues as E-book/E-Magazine per month. You can download their issues from their official websites itself. That is,

http://therubyist.com/

http://railsmagazine.com/

Download and Enjoy :)

Keep on improve your skills and knowledge in Ruby On Rails.

creating a directory using ruby

2009-02-16T02:35:00.000-08:00

Creates a directory and all its parent directories. For example,

FileUtils.mkdir_p '/usr/local/lib/ruby'

causes to make following directories, if it does not exist.

* /usr
* /usr/local
* /usr/local/lib
* /usr/local/lib/ruby

You can pass several directories at a time in a list.

2009-02-04T06:28:00.000-08:00

submit_tag will be override the functionality reset in Rails.

Eg: Reset tag in Rails
<%= submit_tag "Reset", :name => 'reset', :type => 'reset', :id => 'task_reset' %>

Documentation with RDoc

2007-11-22T22:53:00.000-08:00

Generating documentation with RDoc

We’ll suppose that your application is a Rails application.

Go to the root of your application
Type rake doc:app

This rake task (that uses RDoc) will start generating the documentation for your application. It will detect every controllers, every models, every helpers, every methods, every attributes, every constants, every whatever and will structure all of this in a logical manner. Then, it will output a bunch of HTML files that you will find in doc/app. Moreover, it will detect every comments you wrote and try to include them at the right place in the doc.

Syntaxes and Examples to do comments on your applications :

Text Decoration :

This method is a very critical one in our system. Please be careful!

The text above is bigger because I used 2 heading characters "==" before typing the actual comment. (It‘s like the h1, h2, h3 tags in HTML but instead you use =, ==, === and so on)

Ordering:

It takes 2 params
We discard the 1st one
We put "mister t" in the second one if nothing has been supplied.

As you can see, you can also create ordered lists with RDoc. Just type a digit and then a period before your comment. If you need a non-ordered list, type * or - before your comment. If you need an alpha list, type a letter followed by a period. Note also that RDoc automatically put hyperlinks around method and class names. That‘s a very easy and useful way to help people navigating in your documentation! Hey let‘s try it…

Hyperlink :

RDoc also detects external links, like www.railsthinker.blogspot.com. If you prefer displaying a label instead of an URL address, use the label[url] format instead, like that : www.railsthinker.blogspot.com. If your label as more than 2 words (like in the example), put them inside curly braces, like that {Rock on!} [the url]

HTML basic formatting :

Finally, how about some HTML basic formatting? if it is just one word long, use * hello * for bold and _ hello _ for italic (just remove the spaces). Now if the thing to format is more than one word long, use the more traditionnal and <em> and <b> tags (just a nitpicky question though : Why "b" instead of "strong"?).

One final note :

RDoc is not specific to Rails. Like I said earlier, it is a ruby library and thus you can use it in other contexts. I took Rails because I knew that the % of people using Ruby without Rails was rather small.

Filters in RoR

2007-10-01T19:53:00.000-07:00

Hi to all,

Filters enable you to write code in your controllers that wrap the processing
performed by actions—you can write a chunk of code once and have it be
called before or after any number of actions in your controller (or your controller’s
subclasses). This turns out to be a powerful facility. Using filters, we
can implement authentication schemes, logging, response compression, and
even response customization.

Rails supports three types of filter: before, after, and around.

before and after filters are invoked before or after
an action. Rails maintains two chains of filters for each controller. When a
controller is about to run an action, it executes all the filters on the before
chain. It executes the action before running the filters on the after chain.

eg: if u want to do the authentication for few files in ur app. Use this following code

put this code in ur applicaion.rb file of ur respective controller:

def authorize
unless User.find_by_id(session[:user_id])
flash[:notice] = "Please log in"
redirect_to(:controller => "login" , :action => "login" )
end
end

put the below in ur controller file. eg: name_controller.rb

class AdminController <>
end

using this filter u can protect each and every methods under this controller.

After Filter:

U can call this method after u executed any methods ( in ur controller ) like the below code:

class AdminController <>
before_filter :authorize
# ....
end

Around Filters

Around filters wrap the execution of actions. You can write an around filter in
two different styles. In the first, the filter is a single chunk of code. That code
is called before the action is executed. If the filter code invokes yield, the action
is executed. When the action completes, the filter code continues executing.
Thus, the code before the yield is like a before filter, and the code after the
yield is the after filter. If the filter code never invokes yield, the action is not
run—this is the same as having a before filter return false.

Example :

around_filter :one, :two
def one
logger.info("start one" )
yield
logger.info("end one" )
end
def two
logger.info("start two" )
yield
logger.info("end two" )
end

Output:

the sequence of log messages will be
start one
start two
. . .
end two
end one

Simple AJAX concept : observe_field

2007-08-25T06:24:00.000-07:00

Hi to all,

There are lot of ways to do AJAX in ruby on rails. This is one of the easiest way i found. Use the observe_field method.

Syntax:

observe_field(field_id, options = {})

Sample Code:

In the view u need to put this code:

Search By:

<%= select("listing", "search_by", [["City","1"],["Zip Code","2"],["State","3"]]) %>

<%=observe_field("listing_search_by", :url=>{:controller=>"search",:action=>"updatefields"},
:update=>"updatefields", :frequency => 0.5)%>

<label id="updatefields">Enter the City</label>

<%= text_field_tag :query%>

Note: frequency determines the speed ( in seconds ) if it less than zero its event time observer.

Controller code:

def updatefields
@rvalue=request.raw_post
if @rvalue == "1"
@value="Enter the City"
elsif @rvalue == "2"
@value="Enter the Zip Code"
else @rvalue == "3"
@value="Enter the State"
end
end

The above sample code is used to display the label. Dynamically search text field's label is going to change... we can manipulate with the data avail in the database also(without reloading the window or browser. ie AJAX). This is easy to learn and simple to use and effective in the output.

Use and Enjoy.....

(If i made any mistake or u need any more clarification on this prompt me at gokulamurthy@gmail.com)